HDLC是CISCO路由器使用的缺省協(xié)議，一臺(tái)新路由器在未指定封裝協(xié)議時(shí)默認(rèn)使用HDLC封裝。本博文將為您詳細(xì)介紹HDLC協(xié)議的有關(guān)命令及配置。

HDLC協(xié)議是一種簡(jiǎn)單、高效的點(diǎn)到點(diǎn)鏈路協(xié)議，主要用于點(diǎn)到點(diǎn)連接的路由器間的通信。HDLC協(xié)議有 Cisco HDLC 和 ISO DHLC 兩種，兩者不能兼容。

銳捷路由器的同步串行口默認(rèn)封裝Cisco HDLC，所以銳捷路由器可以和Cisco路由器直接相連，但如果把銳捷路由器和不支持Cisco HDLC的路由器相連，就需要采用其它協(xié)議(如PPP)。

1.有關(guān)命令

端口設(shè)置

注:1.以下給出一個(gè)顯示Cisco同步串口狀態(tài)的例子.

Router#show interface serial 0

Serial 0 is up, line protocol is up

Hardware is MCI Serial

Internet address is 150.136.190.203, subnet mask is 255.255.255.0

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255

Encapsulation HDLC, loopback not set, keepalive set (10 sec)

Last input 0:00:07, output 0:00:00, output hang never

Output queue 0/40, 0 drops; input queue 0/75, 0 drops

Five minute input rate 0 bits/sec, 0 packets/sec

Five minute output rate 0 bits/sec, 0 packets/sec

16263 packets input, 1347238 bytes, 0 no buffer

Received 13983 broadcasts, 0 runts, 0 giants

2 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 2 abort

22146 packets output, 2383680 bytes, 0 underruns

0 output errors, 0 collisions, 2 interface resets, 0 restarts

1 carrier transitions

2.　舉例

設(shè)置如下：

Router1:

interface Serial0

ip address 192.200.10.1 255.255.255.0

clockrate 1000000

Router2:

interface Serial0

ip address 192.200.10.2 255.255.255.0

!

3.　舉例使用E1線路實(shí)現(xiàn)多個(gè)64K專(zhuān)線連接.

相關(guān)命令:

注: 1. 當(dāng)鏈路為T(mén)1時(shí),channel-group編號(hào)為0-23, Timeslot范圍1-24; 當(dāng)鏈路為E1時(shí), channel-group編號(hào)為0-30, Timeslot范圍1-31.

2.使用show controllers e1觀察controller狀態(tài),以下為幀類(lèi)型為crc4時(shí)controllers正常的狀態(tài).

Router# show controllers e1

e1 0/0 is up.

Applique type is Channelized E1 - unbalanced

Framing is CRC4, Line Code is HDB3　No alarms detected.

Data in current interval (725 seconds elapsed):

0 Line Code Violations, 0 Path Code Violations

0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins

0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

Total Data (last 24 hours) 0 Line Code Violations, 0 Path Code Violations,

0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins,

0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs

以下例子為E1連接3條64K專(zhuān)線, 幀類(lèi)型為NO-CRC4,非平衡鏈路,路由器具體設(shè)置如下:

shanxi#wri t

Building configuration...

Current configuration:

!

version 11.2

no service udp-small-servers

no service tcp-small-servers

!

hostname shanxi

!

enable secret 5 $1$XN08$Ttr8nfLoP9.2RgZhcBzkk/

enable password shanxi

!

!

ip subnet-zero

!

controller E1 0

framing NO-CRC4

channel-group 0 timeslots 1

channel-group 1 timeslots 2

channel-group 2 timeslots 3

!

interface Ethernet0

ip address 133.118.40.1 255.255.0.0

media-type 10BaseT

!

interface Ethernet1

no ip address

shutdown

!

interface Serial0:0

ip address 202.119.96.1 255.255.255.252

no ip mroute-cache

!

interface Serial0:1

ip address 202.119.96.5 255.255.255.252

no ip mroute-cache

!

interface Serial0:2

ip address 202.119.96.9 255.255.255.252

no ip mroute-cache

!

no ip classless

ip route 133.210.40.0 255.255.255.0 Serial0:0

ip route 133.210.41.0 255.255.255.0 Serial0:1

ip route 133.210.42.0 255.255.255.0 Serial0:2

!

line con 0

line aux 0

line vty 0 4

password shanxi

login

!

end

3、配置keepalive時(shí)間

HDLC每隔10秒鐘就互相發(fā)送鏈路探測(cè)的協(xié)商報(bào)文(KeepAlive報(bào)文)，用于探查鏈路是否中斷，每次收發(fā)的報(bào)文按序號(hào)遞增，序號(hào)失序則鏈路中斷。當(dāng)接口連續(xù)3次(數(shù)據(jù)包速率超過(guò)1000packets/s時(shí)為6次)沒(méi)有收到對(duì)方對(duì)自己的遞增序號(hào)的確認(rèn)時(shí)，HDLC協(xié)議就把鏈路狀態(tài)由Up轉(zhuǎn)變?yōu)镈own，鏈路將不可用。

HDLC協(xié)議可配置的參數(shù)只有Keepalive的間隔時(shí)間，缺省值是10秒?？梢愿鶕?jù)鏈路的流量來(lái)修改這個(gè)值。

1、配置keepalive時(shí)間：

Router(config)#interface interface-id

Router(config-if)#keepalive seconds

interface 命令用于指定要配置的接口，必須是Serial口，interface-id是接口號(hào)。

keepalive 命令設(shè)置keepalive時(shí)間，seconds是以秒為單位的時(shí)間值。

2、忽略keepalive探查：

Router(config)#interface interface-id

Router(config-if)#no keepalive

使用 no keepalive 命令表示不進(jìn)行HDLC鏈路狀態(tài)探查，即不發(fā)送keepalive報(bào)文，也不處理收到的keepalive報(bào)文。

配置舉例：

R1>enable R1#configure terminal R1(config)#interface s0/0 R1(config-if)#encapsulation hdlc R1(config-if)#keepalive 15

R2>enable R2#configure terminal R2(config)#interface s0/0 R2(config-if)#encapsulation hdlc R2(config-if)#keepalive 15

注意：你必須保證相連兩端的keepalive時(shí)間相同。